Frequency dependence of Q in the mantle underlying the shield areas of eurasia
Abstract
In Part I the results of short and intermediate period data analyses for the determination of a frequency dependent Q model of the mantle under the shield areas of Eurasia are presented. The spectra of short period P waves from nuclear explosions in the 1-8 Hz frequency range give t* sub p = approx. 0.15-0.2 seconds. Part II presents analyses of long period data. Long period multiple S and ScS phases observed in northern Europe were analyzed to determine mantle attenuation in the 0.02 to 0.2 Hz range under the Eurasian shield. Two groups of events are used: deep Far-Eastern earthquakes and large earthquakes near the edges of the shield areas of Eurasia. Part III provides the Q model. A large set of broad band data was analyzed to determine the frequency and depth dependence of Q for P and S waves under the northern shield areas of Eurasia. A wide range of techniques utilizing spectra, amplitude ratios and waveform modeling were used to derive apparent and absolute t* estimated for P and S waves covering the seismic band between 0.01 to 10 Hz. A supplement discusses methodologies for estimating t*(f) from Short Period Body Waves and Regional Variations of t*(f) in the United States.
- Publication:
-
Final Technical Report
- Pub Date:
- January 1985
- Bibcode:
- 1985tege.rept.....D
- Keywords:
-
- Asia;
- Earth Mantle;
- Europe;
- Seismology;
- Amplitudes;
- Bearing (Direction);
- Broadband;
- Dependence;
- Depth;
- Detection;
- Earth Planetary Structure;
- Earthquakes;
- Frequencies;
- Mathematical Models;
- Nuclear Explosions;
- P Waves;
- Ratios;
- S Waves;
- Seismic Waves;
- Spectrum Analysis;
- United States;
- Wave Attenuation;
- Waveforms;
- Geophysics